C# and .NET for Android and iPhone development
As the project mono progresses we have two products being rolled out commercially viz Mono Droid and Mono Touch.
The android version is still beta and can be downloaded for free, they integrate with VS 2010 only. I couldn't find an open source mono version for both the development stacks, but there is a possibility that they exist. Will find out tonight.
Θ Ω Sushant ♂